Defining and initialize a class property in PHP Laravel controller - php

Question

I try defined property for some controller and i get error :
Symfony \ Component \ Debug \ Exception \ FatalErrorException (E_UNKNOWN)
Constant expression contains invalid operations
This my controller code :
namespace App\Http\Controllers...;
use Illuminate\Http\Request;
use App\Http\Controllers\Controller;
use App\Customer;
use App\City;
use Illuminate\Database\Eloquent\Builder;
use Carbon\Carbon;
use Illuminate\Support\Facades\Auth;
class CatalogController extends Controller
{
protected $user = Auth::user();
function user() {
$user = optional(Auth::user())->load(['city']);
return $user;
}
}
In php.net I read this:
Class member variables may be initialized, but this initialization must be a constant value--that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.
I assume that this rule is not executed in my code. Am I right?

Answer 1

Retrieving the user in a controller method is fine because it is only executed once for the request. There is no need to advantage to storing it as instance property because a new instance of the controllers is made for every request.
You could use the following code:
public function index()
{
$user = Auth::user()->with('city')->get();
$articles = $this->getArticlesForUser($user);
return view('home', [
'user' => $user
]);
}
public function getArticlesForUser(User $user){
// Do something with $user
return [];
}
public function delete()
{
$user = Auth::user();
$user->delete();
return view('home');
}
If the goal is to have calculate the values once and use them at various places a singleton can be used:
<?php
class Settings {
private $accessToken = '';
private $items = [];
private static $instance = null;
protected function __construct(){}
public static function getInstance(){
if(static::$instance == null){
static::$instance = static::buildInstance();
}
return static::$instance;
}
private static function buildInstance(){
$instance = new Settings();
$instance->accessToken = md5(rand(1,1000));
$instance->items = [1,2,3];
return $instance;
}
public function getToken(){
return $this->accessToken;
}
}
$settings = Settings::getInstance();
// Both return the same token because the instance is the same
var_dump($settings->getToken());
var_dump(Settings::getInstance()->getToken());

Answer 2

You should assign your properties in constructor like this
protected $user;
public function __construct()
{
$this->user = Auth::user();
}
or through setters...
Edit
However in your case it's not a good idea please see https://laravel.com/docs/5.3/upgrade#5.3-session-in-constructors